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oracle集合union、union all、intersect、minus

2012-08-25 13:15 495 查看

oracle中集合的效率比普通的比较要高

测试案例

--测试表数据

SQL> select stuid from zr_stu;

STUID
-----------
1
2
3
4
5
6
7

7 rows selected

Executed in 0.14 seconds

--表数据

SQL> select stuid from zr_stu where stuid > 3;

STUID
-----------
4
5
6
7

Executed in 0.047 seconds

SQL> select stuid from zr_stu where stuid < 6;

STUID
-----------
1
2
3
4
5

Executed in 0.109 seconds

--union

SQL> select stuid from zr_stu where stuid > 4 union select stuid from zr_stu where stuid < 6;

STUID
----------
1
2
3
4
5
6
7

7 rows selected

Executed in 0.031 seconds

--union all

SQL> select stuid from zr_stu where stuid > 4
2  union all
3  select stuid from zr_stu where stuid < 6;

STUID
----------
5
6
7
1
2
3
4
5

8 rows selected

Executed in 0.156 seconds

--intersect

SQL> select stuid from zr_stu where stuid > 4
2  intersect
3  select stuid from zr_stu where stuid < 6;

STUID
----------
5

Executed in 0.078 seconds

--minus

SQL> select stuid from zr_stu where stuid > 4
2  minus
3  select stuid from zr_stu where stuid < 6;

STUID
----------
6
7

Executed in 0.062 seconds

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标签： oracle sql 测试

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